Method of Making Foams Using Partial Molds

ABSTRACT

A method of making a foamed article, for example a foamed component for an article of footwear, includes forming an unfoamed, thermoplastic polymer into an unfoamed article; heating the article to soften the article and infusing the softened article with at least one inert gas at a first pressure greater than atmospheric pressure that is sufficient to cause the at least one inert gas to permeate into the softened article; and reducing the pressure to second pressure below the first pressure with the unfoamed article softened to at least partially foam the article. A surface of a partial mold limits foam expansion in at least one direction but less than all directions. The article or a part of the article may be formed from an unfoamed structure of interconnected, unfoamed, thermoplastic polymeric members spaced to define openings between the thermoplastic polymeric members.

RELATED APPLICATION DATA

This application is: (a) a continuation of U.S. patent application Ser.No. 16/915,325, filed Jun. 29, 2020, which application is (b) acontinuation of U.S. patent application Ser. No. 16/120,395, filed Sep.3, 2018 (now U.S. Pat. No. 10,730,231, granted Aug. 4, 2020), whichapplication is (c) a continuation of U.S. patent application Ser. No.14/924,263, filed Oct. 27, 2015 (now U.S. Pat. No. 10,065,368, grantedSep. 4, 2018), which application (d) claims priority to U.S. ProvisionalPatent Application No. 62/075,529, filed Nov. 5, 2014, whichapplications are incorporated herein in their entirety by reference.

FIELD

The present disclosure relates to methods for forming foams,particularly flexible foams, using molds and articles made by themethods.

INTRODUCTION

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Flexible foams are used for cushioning, support, and to absorb impacts,for example in seats and furniture, footwear, packaging, straps,protective gear, and so on. In general, foam materials are made insheets or blocks and cut to a desired pre-form shape, then finished to afinal shape.

Foamed midsoles for athletic footwear may be made from crosslinkedpoly(ethylene co-vinyl acetate) (EVA), for example, which may be cutfrom a block or sheet of foam. Injection molding may typically not beused because foam materials made by this method must have higherspecific gravities to foam uniformly. A new mold must be made toinjection mold a midsole of a new design.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a perspective view of an example according to the disclosedtechnology.

FIG. 2 is a perspective view of a second example of the disclosedtechnology.

FIGS. 3A-3F are examples of components 3 of FIG. 2 .

FIG. 4 is a perspective view of an example of a partial mold.

FIG. 5 is a perspective view of a second example of a partial mold.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings. The figures are representative ofembodiments according to the disclosed technology, but are notnecessarily shown to scale.

DESCRIPTION

A method of making a closed-cell foamed article, for example a foamedcomponent for an article or footwear, comprises providing an unfoamed,thermoplastic polymeric article; heating the article to soften thearticle and infusing the softened article with at least one inert gas ata first pressure that is sufficient to cause the at least one inert gasto permeate into the softened article; and, while the article issoftened, reducing the pressure to second pressure below the firstpressure to at least partially foam the article, wherein a surface of apartial mold limits foam expansion in at least one direction but lessthan all directions. The unfoamed article may be provided by depositingunfoamed, thermoplastic polymer onto a support surface in athree-dimensional printing process to form the unfoamed article. Theunfoamed article may comprise interconnected, unfoamed, thermoplasticpolymeric members spaced to define openings therebetween. Alternatively,an unfoamed article infused with at least one inert gas may be provided,then heated at a first pressure to soften the article followed by areduction in pressure so that the softened article at least partiallyfoams, again using a partial mold to limit foam expansion in at leastone direction but less than all directions during the foaming step. Apartial mold does not fully enclose the article during foaming. As thearticle is not fully enclosed during the foaming, the infused gaspresent in the article is able to escape from at least a portion of anouter surface of the article, and from the partial mold. The partialmold may be adjacent to the article before foaming begins or the articlemay come into contact with a surface of the partial mold during foamingto prevent the article from expanding further during foaming in thedirection of the surface of the partial mold. The surface of the partialmold that limits foam expansion may be flat and may optionally includeone or more spaces through which the structure can expand beyond thesurface during foaming. The outer surfaces of the article before thefoaming may define a top, a bottom opposite the structure top, and anouter circumference between the top and the bottom, and the surface ofthe partial mold may limit foam expansion of at least a part of theouter circumference. The surface of the partial mold may limit foamexpansion to expansion in directions of the top or the bottom or boththe top and the bottom. In another example, the partial mold may have abottom surface and a side surface or side surfaces that limit foamexpansion and may be open in a direction opposite the bottom surface.The partial mold may include a bottom portion and a side portion, andthe side portion may or may not completely surround the article beingfoamed. The partial mold may have adjacent sections that separate duringfoaming of the article. For example, the partial mold may have a firstmold part comprising the bottom surface and a second mold partcomprising the side surfaces, wherein the first and second mold partsare adjacent but not conjoined, in which case the second mold part maybe moved away from the first mold part before unmolding the foamedarticle from the second mold part. The partial mold may be in placebefore the unfoamed, thermoplastic polymer is deposited onto a supportsurface to form the article or may be put into position after thethree-dimensional printing process but before heating the article tocause the at least one inert gas to permeate into the softened article.

In any of these examples, the partial mold may have a surface thatimparts a pattern or decoration on at least a portion of the foamedarticle. In any of these examples, the partial mold may have a shape ofa midsole for footwear. The shape may be that of a perimeter of amidsole or a part of a perimeter of a midsole. In any of these examples,the partial mold may be of a sacrificial nature that is destroyed inremoving the molded, foamed article. For example, the partial mold or aportion of the partial mold may be cut away or torn away after thearticle is molded. In another example, the partial mold or a portion ofthe partial mold may be melted or dissolved after the article is molded.In yet another example, the partial mold or a portion of the partialmold may become a part of the foamed article, for example the partialmold or a portion of the partial mold may be may become a layer orcomponent of a midsole for footwear that is foamed and shaped by thepartial mold. In such instances, the partial mold or a portion of thepartial mold may be adhesively attached or physically attached duringthe foaming and molding process. In any of these examples, the foamedarticle may be heated to soften the article a second time, infused witha second at least one inert gas at a third pressure that is sufficientto cause the second at least one inert gas to permeate into the softenedarticle; then the pressure is reduced while the first polymeric resin isor remains softened to further foam the article, optionally again usinga partial mold to limit foam expansion in at least one direction butless than all directions. Examples of articles that may be made by thesemethods are footwear uppers, footwear collars, footwear tongues,footwear insoles, footwear midsoles, shinguards, shoulder pads, chestprotectors, masks, helmets, headgear, knee protectors, articles ofclothing, straps, furniture cushions, and bicycle seats and foamedcomponents for such articles.

Also disclosed is a method of making a closed-cell foamed article, forexample a foamed component for an article or footwear, comprisingproviding an unfoamed, thermoplastic polymeric article infused with atleast one inert gas; heating the article to soften the article at afirst pressure and, while the article is softened, reducing the pressureto second pressure below the first pressure to at least partially foamthe article, wherein a surface of a partial mold limits foam expansionin at least one direction but less than all directions.

A method of making a foamed article, for example a foamed component foran article or footwear, comprises heating a thermoplastic article, whichmay comprise interconnected, unfoamed, thermoplastic polymeric members,the article being infused with at least one inert gas, to a firsttemperature to soften the article to at least partially foam, wherein asurface of a partial mold limits foam expansion in at least onedirection but less than all directions. The thermoplastic article may bemade of a thermoplastic elastomer composition. The thermoplastic articlemay be infused with inert gas below or up to a saturation point. Inother words, the thermoplastic article may be infused with the inert gasat a concentration below the saturation point, or at the saturationpoint. When the article includes interconnected, unfoamed, thermoplasticpolymeric members, the first temperature is below a temperature at whichthe structure would collapse but high enough to soften the thermoplasticarticle and allow the thermoplastic article to at least partially foam,wherein a surface of a partial mold limits foam expansion in at leastone direction but less than all directions. The partial mold may have aflat surface, or may have a curved surface, or may have at least oneflat and at least one curved surface, and may optionally contain spacesthrough which the foam may expand.

When the article includes unfoamed, thermoplastic polymeric members,they are spaced to define openings between the unfoamed, thermoplasticpolymeric members. Each opening may have at least one dimension that isgreater than at least one dimension of at least one adjacent unfoamedthermoplastic polymeric member. All or some of the openings may beinterconnected. Thermoplastic polymeric members may enclose all or someof the openings. After the thermoplastic polymeric members at leastpartially foam, openings may remain between a portion of or between allof the thermoplastic polymeric members. At least a portion of theinterconnected thermoplastic polymeric members may be arranged in arepeating pattern, for example a pattern that repeats in twoperpendicular directions, or example a regular three-dimensional latticepattern with uniform repeating units. The thermoplastic polymericmembers may have a cross-sectional shape that is circular, oval, square,rectangular, or other polygonal shape, or that is irregularly shaped.The partial mold may be adjacent the structure before foaming begins orthe structure may come into contact with a surface of the partial moldduring foaming to prevent the structure from expanding further duringfoaming in the direction of the surface of the partial mold. The inertgas may be a noble gas, nitrogen, carbon dioxide, or any combinationthereof. The thermoplastic polymeric members may be heated to the firsttemperature at a first pressure, then the pressure may be reduced to asecond pressure less than the first pressure to allow the thermoplasticpolymeric members to at least partially foam. The first pressure may begreater than atmospheric pressure.

A method of making a closed-cell foamed article, for example a foamedcomponent for an article or footwear, comprises forming an articleincluding a structure of interconnected, unfoamed, thermoplasticpolymeric members spaced to define openings between the thermoplasticpolymeric members. Each opening may have at least one dimension that isgreater than at least one dimension of at least one adjacent unfoamedthermoplastic polymeric member. All or some of the openings may beinterconnected. Thermoplastic members may enclose all or some of theopenings. At least a portion of the interconnected thermoplasticpolymeric members may be arranged in a repeating pattern, for example apattern that repeats in two perpendicular directions, for example aregular three-dimensional lattice pattern with uniform repeating units.The structure may be made by printing a thermoplastic polymeric materialwith a three-dimensional printer in a unitary article of theinterconnected thermoplastic polymeric members. The thermoplasticpolymeric material may be a thermoplastic elastomer composition. Thethermoplastic polymeric members may have a cross-sectional shape that iscircular, oval, square, rectangular, or other polygonal shape, or thatis irregularly shaped. In a first location, the thermoplastic polymericmembers are heated to a first temperature below a temperature at whichthe structure collapses to soften the thermoplastic polymeric membersand the softened thermoplastic polymeric members are infused with atleast one inert gas at a first pressure. The inert gas may be a noblegas, nitrogen, carbon dioxide, or any combination thereof. The amount ofinert gas infused into the thermoplastic polymeric members may be belowor up to a saturation point. The first pressure is sufficient to causethe at least one inert gas to permeate into the softened thermoplasticpolymeric members. The first pressure can be greater than atmosphericpressure. After being infused with the inert gas, the thermoplasticpolymeric members are cooled to a second temperature, and the pressureis reduced, for example, to atmospheric pressure. The cooled structureis transferred to a partial mold in a second location; and thethermoplastic polymeric members are heated to a third temperature belowa temperature at which the structure collapses to soften thethermoplastic polymeric members and at least partially foam thethermoplastic polymeric members, wherein a surface of the partial moldlimits foam expansion in at least one direction but less than alldirections. During this step, the pressure is a pressure at which theinfused inert gas will partition out of the softened thermoplasticmembers, causing the softened thermoplastic to foam. The second locationmay be remote, such as a location in a different building from abuilding in which the article is infused with the at least one inertgas. The third temperature may be the same as or different from thefirst temperature. The thermoplastic polymeric members may be heated tothe third temperature at a second pressure greater than atmosphericpressure, then the pressure may be reduced to a third pressure less thanthe second pressure to allow the thermoplastic polymeric members to atleast partially foam.

A method of making a closed-cell foamed article, for example a foamedcomponent for an article or footwear, comprises forming a structurecomprising interconnected, unfoamed, thermoplastic polymeric membersspaced to define openings between the thermoplastic polymeric members.Each opening may have at least one dimension that is greater than atleast one dimension of at least one adjacent unfoamed thermoplasticpolymeric member. All or some of the openings may be interconnected.Thermoplastic members may enclose all or some of the openings. At leasta portion of the interconnected thermoplastic polymeric members may bearranged in a repeating pattern, for example a pattern that repeats intwo perpendicular directions, for example a regular three-dimensionallattice pattern with uniform repeating units. The article may be made byprinting a thermoplastic polymeric material with a three-dimensionalprinter as an article of the interconnected thermoplastic polymericmembers. The thermoplastic polymeric material may be a thermoplasticelastomer composition. The thermoplastic polymeric members may have across-sectional shape that is circular, oval, square, rectangular, orother polygonal shape, or that is irregularly shaped. The foamablearticle may include portions other than the thermoplastic polymericmembers, which portions may be interior or exterior portions. Aninterior portion may be, for example, an interior solid portion ofregular geometric shape or of irregular shape. An exterior portion mayform at least a portion of a side or perimeter of the article, which maybe of uniform or non-uniform thickness, and which may include extensionsinto the article. The article may include a first kind of interconnectedthermoplastic polymeric members that are softened and infused with theat least one inert gas and a second kind of interconnected thermoplasticpolymeric members that are not softened and/or infused with the at leastone inert gas under the conditions at which the first kind ofinterconnected thermoplastic polymeric members are softened and infused.These features may be included in the article by using more than onematerial in printing the article by three-dimensional printing. Thethermoplastic polymeric members are heated to a first temperature belowa temperature at which the structure collapses to soften thethermoplastic polymeric members and the softened thermoplastic polymericmembers are infused with at least one inert gas at a first pressuregreater than atmospheric pressure. The inert gas may be a noble gas,nitrogen, carbon dioxide, or any combination thereof. The amount ofinert gas infused into the thermoplastic polymeric members may be belowor up to a saturation point. The first pressure is sufficient to causethe at least one inert gas to permeate into the softened thermoplasticpolymeric members. The pressure is reduced to second pressure below thefirst pressure while the first polymeric resin is or remains at or belowa temperature at which the structure collapses and at which thethermoplastic polymeric members are softened to at least partially foamthe thermoplastic polymeric members, wherein a surface of a partial moldlimits foam expansion in at least one direction but less than alldirections.

The foamed article made with the partial mold may be subjected to asecond foaming step by heating the at least partially foamed,thermoplastic article to a second temperature to soften thethermoplastic article and infusing the softened thermoplastic articlewith at least one inert gas at a third pressure that is sufficient tocause the at least one inert gas to permeate into the softened article,and then reducing the pressure to fourth pressure below the secondpressure while the first polymeric resin is or remains at a temperatureat which the article is softened to further foam the thermoplasticarticle, optionally again using a surface of a partial mold to limitfoam expansion in at least one direction but less than all directions.The third pressure may be greater than atmospheric pressure. The secondtemperature may be the same as or different from the first temperature.The at least one inert gas used in the second foaming step may be thesame as or different from the inert gas used in the original foamingstep. Suitable examples of the inert gas are again noble gasses,nitrogen, carbon dioxide, or any combination of these. The amount ofinert gas infused into the thermoplastic article may be below or up to asaturation point. The third pressure is sufficient to cause the at leastone inert gas to permeate into the softened thermoplastic polymericmembers and can be the same as or different from the first pressure. Thepressure is reduced to fourth pressure below the first pressure whilethe first polymeric resin is or remains at or below a temperature atwhich a structure of the article made of thermoplastic polymeric memberscollapses to further foam the thermoplastic article. The fourth pressurecan be the same as or different from the second pressure. The secondfoaming step can produce a foamed article of a lower density. The secondfoaming step may also be used for further shaping the foamed article,for example when the second foaming step is carried out in a mold orwith a partial mold.

In any of these methods, the partial mold may be incorporated in orattached to the foamed article during the foaming step.

The disclosed methods allow a foamed article of a desired shape to bemade without tooling for injection molding a foam into a desired shape.The thermoplastic polymeric members of the disclosed methods can beselected to have dimensions that facilitate adsorption of the inert gasand provide desired cushioning, support, and impact resistance withinexpensive equipment in molding the foam.

When the article includes thermoplastic polymeric members, the structureshould not collapse when the article is heated to a temperature tosoften the thermoplastic polymeric members to infuse them with the atleast one inert gas or to cause the infused polymeric members to foam.The structure is considered to have collapsed if the total combinedvolume of its openings decreases more than 50% as a result ofdeformation of its polymeric members from the heat. It is desirable forthe total combined volume of openings of the structure to decrease bynot more than 20% or by not more than 10% or by not more than 5% or bynot more than 1% or not to decrease by any noticeable amount(substantially 0%). The article or any thermoplastic polymeric membersof the article may have a cross-sectional shape that is generallycircular, oval, square, rectangular, or other polygonal shape, or thatis irregularly shaped. “Generally” is used here to indicate an overallshape that may have imperfections and irregularities, such as bumps,dents, and so on.

The foamed article may be a midsole or midsole pre-form for an articleof footwear. The foamed article may be incorporated as cushioning intoother articles. As nonlimiting examples, the foamed article may be afoamed element in footwear, such as a part of a footwear upper, such asa foamed element in a collar, a midsole or a part of a midsole, or anoutsole or a part of an outsole; foam padding in shinguards, shoulderpads, chest protectors, masks, helmets or other headgear, kneeprotectors, and other protective equipment; an element placed in anarticle of clothing between textile layers; or may be used for otherknown padding applications for protection or comfort, such as for apillow, cushion, or in an article or furniture. In various embodiments,the molded article is a midsole for an article of footwear. A midsoleprovides cushioning in the footwear. A midsole should be durable butalso preferably adds as little weight as possible to the footwear whilestill cushioning to the desired degree. A midsole also should be able tobe bonded to an outsole, an upper, or any other components (e.g., ashank, an airbag, or decorative components) in making an article offootwear.

As used in this description, “a,” “an,” “the,” “at least one,” and “oneor more” indicate interchangeably that at least one of the item ispresent; a plurality of such items may be present unless the contextunequivocally indicates otherwise. All numerical values of parameters(e.g., of quantities or conditions) in this specification, including theappended claims, are to be understood as being modified in all instancesby the term “about” whether or not “about” actually appears before thenumerical value. “About” indicates that the stated numerical valueallows some slight imprecision (with some approach to exactness in thevalue; approximately or reasonably close to the value; nearly). If theimprecision provided by “about” is not otherwise understood in thetechnological field with this ordinary meaning, then “about” as usedherein indicates at least variations that may arise from ordinarymethods of measuring and using such parameters. In addition, disclosuresof ranges are to be understood as specifically disclosing all values andfurther divided ranges within the range. The terms “comprising,”“including,” and “having” are inclusive and therefore specify thepresence of stated features, steps, operations, elements, or components,but do not preclude the presence or addition of one or more otherfeatures, steps, operations, elements, or components. Orders of steps,processes, and operations may be altered when possible, and additionalor alternative steps may be employed. As used in this specification, theterm “or” includes any one and all combinations of the associated listeditems.

The thermoplastic article is made from a thermoplastic polymericcomposition. The thermoplastic article can be made by one or moreforming methods, including molding, cutting, extrusion, andthree-dimensional printing. The thermoplastic article may be or includea structure of interconnected thermoplastic polymeric members spaced todefine openings between the thermoplastic polymeric members can beformed by three-dimensional printing a thermoplastic polymericcomposition. A thermoplastic polymeric composition, which may include athermoplastic elastomer, and which is suitable for foaming with at leastone inert gas, can be extruded into a length (a “filament”) having anappropriate cross-section for processing through a three-dimensionalfabricator or printer. The three-dimensional fabricator deposits a meltof the thermoplastic polymeric composition in a pre-determined patternonto a surface in a process that is also known as three-dimensionalprinting. The process is described in detail in a number ofpublications, for example in US Patent Application Publication No.2012/0241993, which is incorporated herein by reference.Three-dimensional fabrication or printing equipment is availablecommercially, for example from MakerBot under the tradename REPLICATOR.

The thermoplastic polymeric composition can include any thermoplasticpolymer, including thermoplastic elastomers that are suitable for theintended use of the foamed article to be made. Nonlimiting examples ofsuitable thermoplastic polymers and elastomers include thermoplasticpolyurethane elastomers, thermoplastic polyurea elastomers,thermoplastic polyamide elastomers (PEBA or polyether block polyamides),thermoplastic polyester elastomers, metallocene-catalyzed blockcopolymers of ethylene and a-olefins having 4 to about 8 carbon atoms,and styrene block copolymer elastomers such aspoly(styrene-butadiene-styrene),poly(styrene-ethylene-co-butylene-styrene), andpoly(styrene-isoprene-styrene).

Thermoplastic polyurethane elastomers may be selected from thermoplasticpolyester-polyurethanes, polyether-polyurethanes, andpolycarbonate-polyurethanes, including, without limitation,polyurethanes polymerized using as polymeric diol reactants polyethersand polyesters including polycaprolactone polyesters. These polymericdiol-based polyurethanes are prepared by reaction of a polymeric diol(polyester diol, polyether diol, polycaprolactone diol,polytetrahydrofuran diol, or polycarbonate diol), one or morepolyisocyanates, and, optionally, one or more chain extension compounds.Preferably the polymeric diol-based polyurethane is substantially linear(i.e., substantially all of the reactants are difunctional).Diisocyanates used in making the polyurethane elastomers may be aromaticor aliphatic, and examples include, without limitation, isophoronediisocyanate (IPDI), methylene bis-4-cyclohexyl isocyanate(H.sub.12MDI), cyclohexyl diisocyanate (CHDI), m-tetramethyl xylenediisocyanate (m-TMXDI), p-tetramethyl xylene diisocyanate (p-TMXDI),4,4′-methylene diphenyl diisocyanate (MDI, also known as4,4′-diphenylmethane diisocyanate), 2,4- or 2,6-toluene diisocyanate(TDI), ethylene diisocyanate, 1,2-diisocyanatopropane,1,3-diisocyanatopropane, 1,6-diisocyanatohexane (hexamethylenediisocyanate or HDI), 1,4-butylene diisocyanate, and the like, which maybe used in combinations. Chain extension compounds, or extenders, havetwo functional groups reactive with isocyanate groups, for example,diols, dithiols, diamines, or compounds having a mixture of hydroxyl,thiol, and amine groups, such as alkanolamines, aminoalkyl mercaptans,and hydroxyalkyl mercaptans, among others. The molecular weight of thechain extenders may range from about 60 to about 400. Alcohols andamines are typically used. Examples of useful diols include ethyleneglycol and lower oligomers of ethylene glycol including diethyleneglycol, triethylene glycol and tetraethylene glycol; propylene glycoland lower oligomers of propylene glycol including dipropylene glycol,tripropylene glycol and tetrapropylene glycol; cyclohexanedimethanol,1,6-hexanediol, 2-ethyl-1,6-hexanediol, 1,4-butanediol, 2,3-butanediol,1,5-pentanediol, 1,3-propanediol, butylene glycol, neopentyl glycol, andcombinations of these. Suitable diamine extenders include, withoutlimitation, ethylene diamine, diethylene triamine, triethylenetetraamine, and combinations of these. Other typical chain extenders areamino alcohols such as ethanolamine, propanolamine, butanolamine, andcombinations of these.

The polyester diols used in forming a thermoplastic polyurethaneelastomer are in general prepared by the condensation polymerization ofone or more polyacid compounds and one or more polyol compounds.Preferably, the polyacid compounds and polyol compounds aredi-functional, i.e., diacid compounds and diols are used to preparesubstantially linear polyester diols, although minor amounts ofmono-functional, tri-functional, and higher functionality materials(perhaps up to 5 mole percent) can be included to provide a slightlybranched, but uncrosslinked polyester polyol component. Suitabledicarboxylic acids include, without limitation, glutaric acid, succinicacid, malonic acid, oxalic acid, phthalic acid, hexahydrophthalic acid,adipic acid, maleic acid, suberic acid, azelaic acid, dodecanedioicacid, their anhydrides and polymerizable esters (e.g., methyl esters)and acid halides (e.g., acid chlorides), and mixtures of these. Suitablepolyols include those already mentioned, especially the diols. Inpreferred embodiments, the carboxylic acid component includes one ormore of adipic acid, suberic acid, azelaic acid, phthalic acid,dodecanedioic acid, or maleic acid (or the anhydrides or polymerizableesters of these) and the diol component includes one or more of includes1,4-butanediol, 1,6-hexanediol, 2,3-butanediol, or diethylene glycol.Typical catalysts for the esterification polymerization are protonicacids, Lewis acids, titanium alkoxides, and dialkyltin oxides.Polylactones, such as polycaprolactone diol, may also be used.

A polymeric polyether may be obtained by reacting a diol initiator,e.g., 1,3-propanediol or ethylene or propylene glycol, with alkyleneoxide chain-extension reagent. Polyethylene oxide (also calledpolyethylene glycol), polypropylene oxide (also called polypropyleneglycol), and block polyethylene oxide-polypropylene oxide copolymers maybe used. Two or more different alkylene oxide monomers may be randomlycopolymerized by coincidental addition or polymerized in blocks bysequential addition. Tetrahydrofuran may be polymerized by a cationicring-opening reaction initiated by formation of a tertiary oxonium ion.Polytetrahydrofuran is also known as polytetramethylene ether glycol(PTMEG).

Aliphatic polycarbonate diols that may be used in making a thermoplasticpolyurethane elastomer are prepared by the reaction of diols withdialkyl carbonates (such as diethyl carbonate), diphenyl carbonate, ordioxolanones (such as cyclic carbonates having five- and six-memberrings) in the presence of catalysts like alkali metal, tin catalysts, ortitanium compounds. Useful diols include, without limitation, any ofthose already mentioned. Aromatic polycarbonates are usually preparedfrom reaction of bisphenols, e.g., bisphenol A, with phosgene ordiphenyl carbonate.

The polymeric diol preferably has a weight average molecular weight ofat least about 500, more preferably at least about 1000, and even morepreferably at least about 1800 and a weight average molecular weight ofup to about 10,000, but polymeric diols having weight average molecularweights of up to about 5000, especially up to about 4000, may also bepreferred. The polymeric diol advantageously has a weight averagemolecular weight in the range from about 500 to about 10,000, preferablyfrom about 1000 to about 5000, and more preferably from about 1500 toabout 4000. The weight average molecular weights may be determined byASTM D-4274. The polymeric diol segments typically are from about 35% toabout 65% by weight of the polyurethane polymer, and preferably fromabout 35% to about 50% by weight of the polyurethane polymer.

Suitable thermoplastic polyurea elastomers may be prepared by reactionof one or more polymeric diamines with one or more of thepolyisocyanates already mentioned and one or more of the diamineextenders already mentioned. Polymeric diamines include polyoxyethylenediamines, polyoxypropylene diamines,poly(oxyethylene-oxypropylene)diamines, and poly(tetramethyleneether)diamines.

Suitable thermoplastic polyamide elastomers may be obtained by: (1)polycondensation of (a) a dicarboxylic acid, such as oxalic acid, adipicacid, sebacic acid, terephthalic acid, isophthalic acid,1,4-cyclohexanedicarboxylic acid, or any of the other dicarboxylic acidsalready mentioned with (b) a diamine, such as ethylenediamine,tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, ordecamethylenediamine, 1,4-cyclohexanediamine, m-xylylenediamine, or anyof the other diamines already mentioned; (2) a ring-openingpolymerization of a cyclic lactam, such as .epsilon.-caprolactam orco-laurolactam; (3) polycondensation of an aminocarboxylic acid, such as6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, or12-aminododecanoic acid; or (4) copolymerization of a cyclic lactam witha dicarboxylic acid and a diamine to prepare a carboxylicacid-functional polyamide block, followed by reaction with a polymericether diol (polyoxyalkylene glycol) such as any of those alreadymentioned. Polymerization may be carried out, for example, attemperatures of from about 180.degree. C. to about 300.degree. C.Specific examples of suitable polyamide blocks include NYLON 6, NYLON66, NYLON 610, NYLON 11, NYLON 12, copolymerized NYLON, NYLON MXD6, andNYLON 46.

Thermoplastic polyester elastomers have blocks of monomer units with lowchain length that form the crystalline regions and blocks of softeningsegments with monomer units having relatively higher chain lengths.Thermoplastic polyester elastomers are commercially available under thetradename HYTREL from DuPont.

Metallocene-catalyzed block copolymers of ethylene and a-olefins having4 to about 8 carbon atoms are prepared by single-site metallocenecatalysis of ethylene with a softening comonomer such as hexane-1 oroctene-1, for example in a high pressure process in the presence of acatalyst system comprising a cyclopentadienyl-transition metal compoundand an alumoxane. Octene-1 is a preferred comonomer to use. Thesematerials are commercially available from ExxonMobil under the tradenameExact™ and from the Dow Chemical Company under the tradename Engage™.

Styrene block copolymer elastomers such aspoly(styrene-butadiene-styrene),poly(styrene-ethylene-co-butylene-styrene), andpoly(styrene-isoprene-styrene) may be prepared may anionicpolymerization in which the polymer segments are produced sequentially,first by reaction of an alkyl-lithium initiator with styrene, thencontinuing polymerization by adding the alkene monomer, then completingpolymerization by again adding styrene. S-EB-S and S-EP-S blockcopolymers are produced by hydrogenation of S-B-S and S-I-S blockcopolymers, respectively.

When the foamable article is formed onto a surface by depositing thethermoplastic polymeric composition in a pre-determinedthree-dimensional shape by three-dimensional printing with athree-dimensional fabricator, the article may include a structure ofinterconnected thermoplastic polymeric members spaced to define openingsbetween them. Each opening may be from about 0.5 mm or from about 1 mmor from about 2 mm to about 5 mm or to about 8 mm or to about 10 mm ineach of its dimensions. The size of the openings can range from 0.5 mmto 10 mm. The size of the openings can range from 1 mm to 10 mm. Thesize of the openings can range from 1 mm to 8 mm. The size of theopenings can range from 2 mm to 5 mm. Each opening may have at least onedimension that is greater than at least one dimension of at least oneadjacent unfoamed thermoplastic polymeric member. For example, when thethermoplastic polymeric members have a circular circumference, theadjacent openings may have at least one dimension that is greater thanthe diameter of a cross-section. In another example, a pattern in whichthe members have thin rectangular shapes, the spaces may have a smallestdimension that is greater than the thickness of the adjacentthermoplastic polymeric members. The openings may be generally elongatedin shape, and may be joined in a generally continuous path betweenopenings in different or opposite faces or surfaces of the article. Eachface of the article may have a plurality of openings, which may begenerally regularly spaced from one another. Opposite faces may haveopenings arranged in a same pattern.

In a structure of interconnected thermoplastic polymeric members spacedto define openings between the thermoplastic polymeric members, eachopening may have at least one dimension that is greater than at leastone dimension of at least one adjacent unfoamed thermoplastic polymericmember. All or some of the openings may be interconnected. All or someof the openings may be enclosed by thermoplastic members. At least aportion of the interconnected thermoplastic polymeric members may bearranged in a repeating pattern, for example a pattern that repeats intwo perpendicular directions, for example a regular three-dimensionallattice pattern with uniform repeating units. The structure may be madeby printing a thermoplastic polymeric material with a three-dimensionalprinter in a unitary article of the interconnected thermoplasticpolymeric members. The thermoplastic polymeric material may be athermoplastic elastomer composition. The thermoplastic polymeric membersmay have a cross-sectional shape that is generally circular, oval,square, rectangular, or other polygonal shape, or that is irregularlyshaped. “Generally” is used here to indicate an overall shape that mayhave imperfections and irregularities, such as bumps, dents, and so on.

The sizes of the openings defined by the interconnected, thermoplasticpolymeric members are reduced during the foaming process. In oneexample, the foamed thermoplastic polymeric members may foam to a sizewhere some or all are adjacent to other foamed thermoplastic polymericmembers. In another example, spaces remain between the thermoplasticpolymeric members after foaming.

For example, the thermoplastic polymeric members may be arranged in apattern that repeats in two directions perpendicular to one another. Thepattern may have at least three repeating units in sequence in at leastone direction. The repeating units may be uniform, for example cubes orother geometric shapes that are of a same size, or the repeating unitsmay vary in a regular or irregular pattern. As an example of a varyingpattern, a circular pattern may expand from a center in a plane or inthree-dimensions.

The partial mold can be put in place before or after the thermoplasticarticle is infused with the inert gas, but before the article is foamed.The partial mold may be or include the surface on which the article isformed by three-dimensional printing.

A partial mold is a mold that, during the expansion that results in thefoaming process, only constrains the article (which may be or include athree-dimensional open lattice structure) in at least one but less thanall directions. The partial mold can be a flat sheet of material ontowhich the thermoplastic polymeric article is deposited or formed, butfrom which the foamed product can be released following the foaming. Inone example, the partial mold can be a mold with a bottom and sidemolding surfaces, but no top molding surface. In another example, thepartial mold can be a mold with constraints around all of a perimeter ofthe component to be formed. In a further example, the partial mold canbe a mold with constraints around only part of a perimeter of thearticle being foamed. For example, when the partial mold is used toshape a midsole for footwear during foaming of the midsole, the partialmold may have only a left or right side of the midsole. If the partialmold constrains the material in two dimensions, the interface betweenthe two dimensions may not be completely sealed, but could just be seton top of each other.

The partial mold can impart a molded pattern or decoration on at least aportion of the constrained surface of the component when foamed.

The partial mold can be put in place before the polymeric resin isdeposited when forming the article by three-dimensional printing. Theprocess of dispensing the polymeric resin can comprise dispensing thepolymeric resin into the partial mold.

The partial mold can simultaneously mold a plurality of components(e.g., a number components laid down on a sheet pan with space betweenthem, so that only their bottom surfaces are constrained, but there issufficient space between them that they remain separated followingfoaming/expansion).

The partial mold can be a sacrificial mold, where the mold is destroyedduring or following the manufacturing process. The mold can be made of amaterial that constrains the polymeric resin or foam for only for partof the manufacturing process, for example, a material which decomposesor melts or burns off or dissolves during the manufacturing process(wax, paper, cornstarch, salt, sugar, a polymer, etc.) either during orafter the foaming step. The sacrificial mold can be formed of a materialfrom which the foamed article can easily be released following themanufacturing process, for example, a sand form which can be easilybroken apart, or a material which can be decomposed, melted, burned offor dissolved following the manufacturing process.

The partial mold can be an article to which at least a portion of thepolymeric resin or foam adheres during the manufacturing process, andwhich may become part of the component formed during the manufacturingprocess. The partial mold may adhere to the polymeric resin during thefoaming step (as the polymeric resin foams and expands). For example,the partial mold could be a midsole component such as an airbag, orcould be an outsole component, such as a rubber component that forms atleast part of an outsole of an article of footwear. The partial moldcould be a thin, clear polymer piece such as a vacuum formed polymercomponent for forming a side of an outsole. The partial mold can beremoved during manufacturing, imparting its shape to the final foamedarticle, or can remain present and form an outer surface of the overallcomponent.

The partial mold can be a thin, optionally clear, polymer piece such asa vacuum formed polymer component for forming a side of an outsole thathas a decorative element (foil, paint, etc.) on at least a portion ofits inner surface. The partial mold can be removed during manufacturing,leaving the decorative element present on an outer surface of the foamedarticle, or can remain present and form an outer surface of the overallcomponent.

The article, which may include a structure of interconnectedthermoplastic polymeric members, is made foamable by heating the articleto a first temperature (which is below a temperature at which anystructure of interconnected thermoplastic polymeric members collapses)to soften the article and infusing the softened article with at leastone inert gas at a first pressure greater than atmospheric pressure thatis sufficient to cause the at least one inert gas to permeate into thesoftened article. The inert gas may be a noble gas, nitrogen, carbondioxide, or any combination of these. The first pressure is sufficientto cause the at least one inert gas to permeate into the softenedarticle. The first exposure is at a pressure and for a length of timesufficient for an amount of the gas to permeate into the softenedarticle to cause at least partial foaming when the pressure is reducedwhen the article is softened. The amount of gas required may depend uponfactors such as the surface area of the article, the type of polymer,the pressure, and the temperature. The infusing step may be continueduntil the point of saturation of the article with the gas.

The article infused with the inert gas may then be cooled to a secondtemperature. The second temperature is one at which the gas with notsignificantly foam the article in a desired length of time. For example,the second temperature may be at or below about 30.degree. C. Then, thepressure may be reduced to atmospheric pressure. The article then is afoamable article. The article can be removed from the pressure vesseland transferred to another location, for example to a partial mold inthe same building or manufacturing site or transferred to a partial moldat a remote site, before it is foamed in the partial mold that limitsfoam expansion in at least one direction but less than all directions.The article is foamed by heating the article to a second temperature tosoften the article to cause the thermoplastic polymeric members to atleast partially foam adjacent or near to a surface of a partial moldthat limits foam expansion in at least one direction but less than alldirections during foaming. When the article includes a structure ofthermoplastic polymeric members, the second temperature is at or below atemperature at which the structure collapses. The second temperature maybe the same as or different from the first temperature at which thearticle was infused with the inert gas. Once the second temperature isreached, the pressure is reduced to a second pressure or released(returned to atmospheric temperature) to cause the thermoplasticpolymeric members to foam in the partial mold.

The article infused with the inert gas may instead be foamed immediatelyafter infusion of the inert gas in the partial mold without interimcooling. Once the softened thermoplastic article has been infused withthe at least one inert gas, the pressure is reduced to a second pressurebelow the first pressure (while the article is below a temperature atwhich a structure of thermoplastic polymeric members would collapse, ifit contains such a structure) to at least partially foam the article ina partial mold. The article remains softened while foaming. For example,the second pressure may be atmospheric pressure.

When the article is foaming, expansion of the article in one or more butless than all directions is constrained by being in direct contact withor coming into direct contact with at least one surface of the partialmold. The foaming article at least partially conforms to the at leastone surface as it presses against the surface during foaming, expandingin one or more of the unconstrained directions.

The article can comprise a second polymeric resin. The second polymericresin can expand and at least partially foam during the manufacturing,optionally at a different rate than the first polymeric resin, or canremain as a solid resin. The second polymeric resin can expand and atleast partially foam at the same expansion ratio as the first polymericresin (so that it expands to the relative dimension as the first resin),or may have a different expansion ratio (so that it expands more or lessthan the first resin).

The foamable thermoplastic article may be foamed a second time byrepeating the process. The at least partially foamed, thermoplasticarticle is heated to a second temperature (which is below a temperatureat which any structure of thermoplastic polymeric members collapses) tosoften the thermoplastic article and the softened thermoplastic articleis again infused with at least one inert gas at a third pressure that issufficient to cause the at least one inert gas to permeate into thesoftened thermoplastic article, then the pressure is reduced to a fourthpressure below the third pressure while the thermoplastic article issoftened to further foam the thermoplastic article, optionally in thesame partial mold or in a second partial mold. A surface unconstrainedduring the first foaming process may be constrained by a surface of thepartial mold during the second foaming process, and vice versa. Thethird pressure may be greater than atmospheric pressure. The secondtemperature may be the same as or different from the first temperatureat which the thermoplastic article was softened and infused during theoriginal foaming process. The inert gas used in the second foamingprocess may be the same as or different from the inert gas used tooriginally at least partially foam the article. Thus, the inert gas maybe a noble gas, nitrogen, carbon dioxide, or any combination of these.The amount of inert gas infused into the thermoplastic article may be upto a saturation point. The third pressure may be the same as ordifferent from the first pressure used in the original infusing stepprocess, so long as it is sufficient to cause the at least one inert gasto permeate into the softened thermoplastic article. The pressure can bereduced to a fourth pressure while the thermoplastic article is softenedto allow the thermoplastic article to further foam, optionally in thesame or a second partial mold. The fourth pressure may be atmosphericpressure.

The article may include a portion that is not infused with the at leastone inert gas and thus not subsequently foamed. The unfoamed portion maybe polymeric or nonpolymeric. If the unfoamed portion is polymeric,either the unfoamed portion does not soften when exposed to the firsttemperature and pressure, does not soften when exposed to the secondtemperature and pressure, or else does not foam when exposed to thesecond temperature/pressure. The unfoamed portion may be in the form ofa solid internal or surface portion of the article or may be a secondstructure of thermoplastic polymeric members. An internal structuralportion may be, for example, a single solid portion. An exteriorstructural portion may be, for example, a solid outer member forming aface of the article.

The closed-cell foamed article may have a top outer surface, an oppositebottom outer surface, and at least one side outer surface having acommon edge with at least one of the top outer surface and the bottomsurface, wherein the side outer surface is free of openings. At leastone surface is shaped by the partial mold.

Among the foamed articles that may be made in this way are footwearuppers, footwear collars, footwear tongues, footwear insoles, footwearmidsoles, shinguards, shoulder pads, chest protectors, masks, helmets,headgear, knee protectors, articles of clothing, straps; furniturecushions, and bicycle seats.

FIG. 1 shows a first partial mold 10 containing a first foamed article12. Article 12 is shaped as a midsole for an article of footwear and hasopenings 13 between foamed, thermoplastic polymeric members 14. Topsurface 15 was not constrained during foaming.

FIG. 2 shows another example of a partial mold, partial mold 110,partially containing midsole article 112. Side 116 of midsole article112 is not constrained during foaming. Midsole article 112 isthree-dimensionally printed using an elastomeric thermoplastic polymercomposition into structures 3. Structures 3 may be printed in variousdifferent configurations, sizes and shapes for example as shown in FIGS.3A, 3B, and 3C, which have interconnected thermoplastic polymericmembers 114 a, 114 b, and 114 c separated by spaces 113 a, 113 b, and113 c forming structures 3 with solid top and bottom portions but opensides; or as shown in FIGS. 3D, 3E, and 3F, which have interconnectedthermoplastic polymeric members 114 d, 114 e, and 114 f separated byspaces 113 d, 113 e, and 113 f forming structures 3 with solid sides andopen tops and bottoms.

FIG. 4 illustrates an example partial mold 210 that may be used infoaming a midsole for an article of footwear. Partial mold 210 has arecessed portion 225 to shape a bottom surface and sides of a midsoleand a raised portion 220 to shape a side of the midsole in the sides ofthe back half of the midsole.

FIG. 5 illustrates an example partial mold 310 that may be used infoaming a midsole for an article of footwear. Partial mold 310 has aflat surface 325 to shape a bottom surface of a midsole (which may bepositioned as shown in dotted outline 330) and a raised portion 320 toshape a side of the midsole in the sides of the back half of themidsole.

Among the foamed articles that may be made in this way are footwearuppers, footwear collars, footwear tongues, footwear insoles, footwearmidsoles, shinguards, shoulder pads, chest protectors, masks, helmets,headgear, knee protectors, articles of clothing, straps; furniturecushions, and bicycle seats.

The foregoing description of particular embodiments illustrate featuresof the invention, but the invention is not limited to any of thespecific embodiments that have been described. The features describedfor particular embodiments are interchangeable and can be used together,even if not specifically shown or described. The same may also be variedin many ways. The invention broadly includes such variations andmodifications.

What is claimed is:
 1. A method of making a closed-cell foamed articlecomprising: a) forming an unfoamed article, the unfoamed articlecomprising unfoamed, thermoplastic polymer formed by interconnected,unfoamed, thermoplastic polymeric members spaced to define openingstherebetween; b) heating the unfoamed article to soften the unfoamedarticle and infusing the softened unfoamed article with at least oneinert gas at a first pressure that is sufficient to cause the at leastone inert gas to permeate into the softened article; and c) reducingpressure to second pressure below the first pressure with the unfoamedarticle softened to at least partially foam the article, wherein asurface of a partial mold limits foam expansion in at least onedirection but less than all directions.
 2. A method according to claim1, wherein during the foam expansion, the surface of the partial moldthat limits the foam expansion includes one or more spaces through whichthe article expands beyond the surface.
 3. A method according to claim1, wherein during the forming, outer surfaces of the unfoamed articleare formed to include a top, a bottom opposite the top, and an outercircumference between the top and the bottom, and wherein during thefoam expansion, the surface of the partial mold that limits the foamexpansion includes at least a part of the outer circumference.
 4. Amethod according to claim 1, wherein during the foam expansion, a bottomsurface and side surfaces of the partial mold limit the foam expansion,and the partial mold is open in a direction opposite the bottom surface.5. A method according to claim 1, wherein the partial mold comprises abottom portion and a side portion, and wherein the partial mold is in ashape of a midsole for footwear.
 6. A method according to claim 1,wherein the partial mold comprises adjacent sections, and wherein duringthe foam expansion, the adjacent sections separate.
 7. A methodaccording to claim 1, further comprising: d) removing the partial moldafter step c) by cutting away or tearing away at least a portion of thepartial mold or by at least partially melting the partial mold.
 8. Amethod according to claim 1, wherein the article is a midsole forfootwear having a first major surface and a second major surfaceopposite the first surface, and wherein a portion of the partial moldbecomes attached to the first major surface or to the second majorsurface.
 9. A method according to claim 1, wherein a portion of thepartial mold becomes adhesively attached to the article.
 10. A methodaccording to claim 1, further comprising: d) heating the at leastpartially foamed article to a second temperature to soften the at leastpartially foamed article and infusing the at least partially foamedarticle with a second at least one inert gas at a third pressure that issufficient to cause the second at least one inert gas to permeate intothe softened at least partially foamed article; and e) reducing pressureto fourth pressure below the third pressure while the at least partiallyfoamed article is or remains softened to further foam the article.
 11. Amethod according to claim 1, wherein the forming step includes formingat least a portion of the interconnected, unfoamed, thermoplasticpolymeric members to be arranged in a repeating pattern, and wherein therepeating pattern repeats in two directions perpendicular to one anotheror has at least three repeating units in sequence in at least onedirection.
 12. A method of making a closed-cell foamed articlecomprising: a) forming an unfoamed article at a first location, thearticle comprising unfoamed, thermoplastic polymer formedinterconnected, unfoamed, thermoplastic polymeric members spaced todefine openings therebetween; b) heating the unfoamed article to a firsttemperature to soften the unfoamed article and infusing the softenedunfoamed article with at least one inert gas at a first pressure that issufficient to cause the at least one inert gas to permeate into thesoftened unfoamed article; c) cooling the unfoamed article to a secondtemperature and reducing pressure to a second pressure; d) transferringthe cooled unfoamed article to a partial mold at a second location; ande) heating the unfoamed article in the partial mold to a thirdtemperature to soften the unfoamed article and at least partially foamthe article, wherein pressure is adjusted to a third pressure sufficientto allow the infused inert gas to partition out of the softened unfoamedarticle to at least partially foam the article, and wherein a surface ofa partial mold limits foam expansion in at least one direction but lessthan all directions.
 13. A method according to claim 12, wherein duringthe foam expansion, the surface of the partial mold that limits the foamexpansion includes one or more spaces through which the article expandsbeyond the surface.
 14. A method according to claim 12, wherein duringthe forming, outer surfaces of the unfoamed article are formed toinclude a top, a bottom opposite the top, and an outer circumferencebetween the top and the bottom, and wherein during the foam expansion,the surface of the partial mold that limits the foam expansion includesat least a part of the outer circumference.
 15. A method according toclaim 12, wherein during the foam expansion, a bottom surface and sidesurfaces of the partial mold limit the foam expansion, and the partialmold is open in a direction opposite the bottom surface.
 16. A methodaccording to claim 15, wherein the partial mold has a first mold partcomprising the bottom surface and a second mold part comprising the sidesurfaces, wherein the first and second mold parts are adjacent but notconjoined, and wherein the method further comprises after step e):moving the second mold part away from the first mold part beforeunmolding the at least partially foamed article from the second moldpart.
 17. A method according to claim 12, wherein the partial moldcomprises a bottom portion and a side portion, and wherein the sideportion incompletely surrounds the article.
 18. A method according toclaim 12, wherein the partial mold comprises a bottom portion and a sideportion, and wherein the partial mold is in a shape of a midsole forfootwear.
 19. A method according to claim 12, wherein the partial moldcomprises adjacent sections, and wherein during the foam expansion, theadjacent sections separate.
 20. A method according to claim 12, whereina portion of the partial mold becomes attached to the article.